The Large Power Plant Effluent Study (LAPPES) was initiated during 1967 in Western Pennsylviania to evaluate the extent and effects of air pollution resulting from the largest complex of coal-burning generating stations in the United States. During 1970 two series of LAPPES field experiments were conducted in an area surrounding the Homer City and Conemaugh Generating Stations; these experiments consisted of ground-based and airborne plume measurements supported by extensive meterological observations. Part 1 of this volume describes the topography and climatology of the generating station complex, the sulfur dioxide and meteorological monitoring equipment, and experimental procedures. Part 2 presents tabulations of plant operational parameters and the air quality and meteorological data collected during 1970.